The goal of this project is to develop new therapeutic agents for "intracellular immunization" against the infection and propagation of HIV. The objectives are to design and test new genes which, upon gene transfer and expression intracellularly, will produce proteins which intervene with the normal functions of HIV. Two major types of therapeutic genes will be tested. The therapeutic genes to be tested are fusions between the genes encoding soluble CD4 (sCD4) and a lysosome targeting protein domain. The author has shown that when two of the fusion genes are expressed, the sCD4 moiety binds HIV glycoprotein gp160 in the endoplasmic reticulum while the lysosome targeting moiety transports the entire complex to the lysosomes for degradation. This scheme is intended to prevent gp160 from reaching the cell surface, thus stopping the assembly of new virions and the propagation of HIV. Dr. Tang will try to establish whether the other two sCD4-fusion genes he has constructed (sCD4-L1 and sCD4-L2) can reverse syncytium formation and degrade gp160 as do the first two genes. He also proposes to find the best constructs for each of four therapeutic genes. This includes the testing of D1 and D1-D2 domains of sCD4 and the use of different lengths and sequences of linkers in the constructs. Next, the author will investigate different "lysosome targeting domains" in the fusion genes and determine their effectiveness in degrading gp160. He will also investigate the routes by which gp160 is being transported to the lysosomes by all effective sCD4-fusion proteins. The author further proposes to clone all effective therapeutic genes with appropriate promoters, transfect them into uninfected CD4+ cells and test them for their ability to resist HIV infection and propagation of the cells. Similar studies with chronically infected H9 and OM10.1 cells will be initiated. The mechanisms of the therapeutic gene products will also be investigated with live HIV.